1. Field of the Invention
This invention relates to a photographic element and a novel development inhibitor precursor for photographic elements. More particularly, this invention relates to a photographic element for color diffusion transfer process using a novel development inhibitor precursor.
2. Description of the Prior Art
Development inhibitors and development inhibitor precursors for use in a photographic element for color diffusion transfer photographic process are known as disclosed in, for example, U.S. Pat. No. 3,260,597 to Weyers et al and U.S. Pat. No. 3,265,498 to Rogers. However, the compounds disclosed in these patents inhibit not only the occurrence of unnecessary development but also the occurrence of necessary development, which results in reducing the quality of images.
Also, photographic development is greatly influenced by temperature, i.e., development proceeds slowly at low temperatures but proceeds faster at higher temperatures and, in particular, development is liable to proceed excessively fast at high temperatures. Therefore, it has been desired to find development inhibitor precursors which enlarge the allowable range of processing temperatures by inhibiting the occurrence of unnecessary development and controlling the necessary development so that it is not implemented at about room temperature, and, in particular, inhibiting the occurrence of excessive development at high temperatures.
U.S. Pat. No. 4,009,029 to Hammond et al discloses some development inhibitor precursors for this purpose. The various photographic additives used in photographic elements must, on the one hand, exhibit their effect but, on the other hand, the additives or the reaction products of the additives must not give undesirable effects such as reduction in image quality before as well as after processing the photographic elements. The compounds described in U.S. Pat. No. 4,009,029, for example, 5-(2-cyanoethylthio)-1-phenyltetrazole form an injurious compound (by product) which promotes the destruction of certain image-forming dyes formed upon processing photosensitive elements. If the additive which forms such an injurious compound exists in a photographic element, the color image density is reduced and the image quality is degraded as time passes after processing. Therefore, it has further been desired to find the development inhibitor precursors which can properly control the occurrence of development, possess a wide allowable range for processing temperature, and reduce the quality of color images after processing less.